React-Native / Realm : how to store an image in the database? - image

My app has to regularly download some content and keep it available offline. I use Realm for that and so far the experience has been great. But I really don't know what to do when it comes to images. I could store a ref to the paths but I'd really prefer Realm's direct storage. Is there a not-too-complex way to achieve that ?
N.B In fact I'd be looking for a snippet like the one above, which would perfectly fill my needs... but this is for IOS, not react-native -> How to put an image in a Realm database?

You can store the base64 string version of the image in Realm. It works great. I am doing that.

I can't seem to find a built it React Native api for dealing with images already stored in memory, and without this it may not make sense to store images in Realm.
It does look like React Native can open images from the filesystem though with paths specified at runtime - https://facebook.github.io/react-native/docs/images.html#network-images
If you take this route you can download/save the image to disk, and simply save the path to the image in Realm.

Related

How to download images for reduce network usage?

I am making android app that must show a lot of images from my REST API. I want to download images, and the next time check for images' name. If the image exists show them from the phone otherwise download from server.
Now I'm using Retrofit for my network requests and Glide for show images. But I have not good idea for solve this issue.
If needed I can change the network library or image loading library.
Thanks in advance
NOTE: This question might be too broad for the liking of S.O.
What you want to do is make what is known as a cache. The idea is that you have a unique identifier (often refered to as a key) for each object in the cache, such as an md5 sum of the image data, or original name + date of creation.
When you want to display an image, you first check if the image exists in the cache. If it exists simply return with the image from cache. if it does not exist, start the download and upon completion you insert the image into the cache.
Here is an example implementation that does what you want. I cannot vouch for it's quality because I never tried it.

How Should I store images - Codeigniter

I'm contemplating on how to store images in my new site.
Should I save the images directly to the database
OR
should I upload them to my server, while storing the path in my database?
Also, should it be the second choice, how does one retrieve the path of a file he uploaded previously?
You should definitely go with the second option as you can take advantage of the user's browser caching these images after the initial request. It also means your database wont be hit constantly for large files which is always a bad thing.
In CodeIgniter there are various parameters you can use to get the name / full file path to store in the database.
See http://ellislab.com/codeigniter%20/user-guide/libraries/file_uploading.html
Also take a look at this great SO question Storing Images in DB - Yea or Nay?
I tried CI's own libraries , its good but not best, Image moo solved all my problems, uploading, resize, crop etc..
http://www.matmoo.com/digital-dribble/codeigniter/image_moo/

openreadAsync vs Bitmap for image downloading from server

I have some image urls which I want to cache locally and save so that I don't need to make a web request again and again as needed.
Now, I am confused whether there is any significant benefit of using webclient's openreadasync method over bitmap for fetching the image for first time for saving it to IsolatedStorage.
For me, I think bitmap would be a better option as I would be able to get a event for progress.
This post gives good info on various image caching options.
http://blogs.msdn.com/b/swick/archive/2011/04/07/image-tips-for-windows-phone-7.aspx
Matt mentioned the fact that default image caching only works per session. So if you are implementing your own Image caching, then you will have to implement a image downloader for which the WebClient OpenReadAsync provides a way to store file locally
If you were't considering a local cache, UriSource would have been the choice.
If you want to cache images beyond the current application instance lifetime, have a look at http://blogs.msdn.com/b/delay/archive/2010/10/04/there-s-no-substitute-for-customer-feedback-improving-windows-phone-7-application-performance-now-a-bit-easier-with-lowprofileimageloader-and-deferredloadlistbox-updates.aspx which will show a way of saving the images to IsolatedStorage and then display it from there. This means you won't have to get it over the network each time the app is run.
If you're using this for lots of images be sure to manage the images you save as well so you don't fill up the disk with lots of old images you'll never need again.

How to cache images and html files in PhoneGap

I need a way for cache images and html files in PhoneGap from my site. I'm planning that users will see site without internet connection like it will be with it. But I see information only about sql data storing, but how can I store images (and use later).
To cache images check out this library -of which I'm the creator-:
imgcache.js
. It's designed for the very purpose of caching images using the local filesystem. If you check out the examples you will see that it can also detect when an image fails to be loaded (because you're offline or you have a very bad connection) and then replaces it automatically with the cached image. The user of the webapp doesn't even notice it's offline.
As for html pages.. if they're html static files, they could be stored locally in the web app (file:// in phonegap).
If they're dynamically generated pages, check the localStorage API if you have a small amount of data, otherwise the filesystem API.
For my web app I retrieve only json data from my server (and process/render it using Backbone+Underscore). The json payload is stored into the localStorage. If the application gets offline, it will fetch json data from the localStorage instead of the server (home-baked fork of Backbone.dualStorage)
You then get the full offline experience: pages+images.
Caching like you might need for simple offline operation is not exactly that easy.
Your first option is the cache manifest. It has some limitations (like the size of the cache) but might work for you since it was designed to do what you want.
Another options is that you can store content on the disk of the device using the file system APIs. This has some drawbacks like security and the fact that you have to load the file from a path / url that is different than you might normally load it from on the web. Check out the hydra plugin for an example of this.
One final option might be to store stuff in localStorage (which has the benefit of being private on all platforms) and then pull it out of there when needed ... that means base64'ing all your images tho so that is a pretty big departure from just standard caching.
Caching is very much possible on Android OS. but on Apple as stated above there are limitations with the size of the images and cache size etc.
If you are willing to integrate and allow the caching on iOS you can use "cache manifest" to do so. but keep the draw backs and limitations in mind.
Also
if you want to save the file to Documents folder under my App, Apple will reject your App. The reason is the system backup all data under Documents folder to iCould after iOS6, so Apple does not allow big data like images or JSON file which could sync from your server again to keep in this folder.
So there is another work around which is good So one can use LocalFileSystem.TEMPORARY instead. It does not save the data to Library/Cache, but it save data to temp folder of App, which does not been auto backup to iCloud and not auto deleted either.
Regards
Rajeev

How do I bulkupload image BLOBs in Google App Engine?

I have a model which *I want* to contain an image blob. I have the images on my local filesystem, but due to the nature of my application, I need to get them in the datastore. Here's my model:
class JeanImage(db.Model):
type = db.StringProperty(required=True, choices=set(["main","front","back","detail"]))
image = db.BlobProperty(required=True)
I haven't tried anything yet because I'm not great when dealing with images.
How can/should I convert my images to blobs so that I can get them in my bulkupload csv file?
Mark
You can do it, just not with the bulk uploader. You need to access the remote api directly.
This site has a basic example of how to use it:
http://www.billkatz.com/2009/2/Remote-API-Hello-World
Its pretty slow and a good idea to have a retry mechanism.
A more detailed description can be found here:
http://code.google.com/appengine/articles/remote_api.html
I believe that what you are trying to achieve is not possible using the app engine bulkloader.
Instead try to create some kind of uploader yourself. For example you could upload the images as a zip file and then extract it an store it in the datastore. The code for that should be fairly straightforward if you can map your images to the datastore entity (e.g. by using a naming convention).

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